.beta.-Glucan is a naturally occurring polysaccharide in the cell walls of cereal grains with its contents ranging from less than one percent in wheat to 16 percent in barley grain. .beta.-Glucan has been extracted from oat and barley grain in small quantities in various laboratories.
Soluble fiber is a desired nutritional component which is lacking in the average American diet. High purity forms of soluble fiber are useful in various food applications to increase the daily soluble fiber consumption to recommended levels. Presently, .beta.-glucan is not available in commercial quantities due to the lack of a successful method for .beta.-glucan extraction.
U.S. Pat. No. 4,028,468 to Hohner et al. (1977) outlines a method to extract .beta.-glucan from oat groat. Groats are hulled, usually crushed grain, especially oats. According to Hohner et al., oat groat is flaked, the oil extracted, dried, ground and air classified to produce a coarse milling fraction. The extraction of .beta.-glucan includes mixing the coarse fraction with water, adjusting the pH twice, chilling the water extract to 4.degree. C., and drying .beta.-glucan in a vacuum dryer. The multiple pH adjustments, the use of oil extraction, air classification and vacuum drying are expensive processing steps which make the invention economically disadvantageous from a commercial production point of view. High purity .beta.-glucan fractions, (over 50 percent pure .beta.-glucan) were not reported using this technique.
U.S. Pat. Nos. 4,804,545 (1989) and 5,013,561 (1991), both to Goering et al., outline a method to extract .beta.-glucan from waxy barley grain. Waxy barley grain is ground and mixed with water, centrifuged to remove bran and starch, boiled to destroy the activity of .beta.-glucanase, centrifuged to remove the coagulated protein which contains a high percentage of oil and the extract passed through an ultrafilter to purify the .beta.-glucan. The .beta.-glucan solids are dried on a drum dryer or a spray dryer. Recovering the solids using this technique with a drum dryer or a spray dryer produces a light yellowish-brown colored product with purity of .beta.-glucan less than 50 percent by weight of the product. These two inventions produce .beta.-glucan products with undesirable .beta.-glucan purity and low molecular weights.
U.S. Pat. Nos. 5,106,640 (1992) and 5,183,677 (1993) both to Lehtomaki et al. outline a method to produce a .beta.-glucan enriched alimentary fiber from oats and barley. Barley or oat grains are dehulled, optionally ground and slurried in water at about 8.degree. C. with ethanol addition. The slurry is screened and a product is collected. The product contains 15-40 percent .beta.-glucan and about equal amounts of starch and some protein. This invention does not produce a .beta.-glucan product having a purity of more than 50 percent by weight of the product.
Because of the high cost and complexity of the previous inventions, it has not been possible to provide a .beta.-glucan product world-wide for food and pharmaceutical uses. Further, the purity of the products from the prior arts are either low or unknown.
In contrast, the present invention provides a method for the recovery of .beta.-glucan from cereal grain which overcomes the disadvantages of the previous inventions. Using the method of the present invention, any person skilled in the art can produce a high purity (60 percent-90 percent) .beta.-glucan product from cereal grains.